In hollow needle tufting machines, as typified by Kile, U.S. Pat. No. 4,549,496 and Davis et al., U.S. Pat. No. 5,588,383, it is important that the knives be precisely aligned with the angular cutting faces of the hollow needles. In prior art tufting machines with hollow needles spaced on two inch centers, a typical two meter tufting machine might have 75 needles. The alignment between the knives and needles in these machines is generally achieved in two steps. First, the knives and needles are mounted as precisely as possible so that the knife blades will be parallel to the angular surfaces of the hollowed needles. Then the tufting machines are operated and because of pressure placed by the knives against the angular cutting surfaces, the knives and needles wear sufficiently to achieve an acceptable alignment.
Historically, the mounting of the hollow needles was itself a time consuming process. Now it has become possible to mount hollow needles more closely to the desired alignment, as in the fashion described in Ingram, U.S. Pat. No. 7,318,383. Therefore, it is desirable to achieve that precise alignment between knife and hollow needle angular cutting surface more easily and without the necessity of operating a tufting machine to achieve the wear-in that has previously provided the final alignment between these parts. In addition, it is desirable to extend the life of the knives and needles and to provide a structure that can be utilized with both fixed knives and knives that are selectively operable to cut only selective yarns. In order to accomplish these and other objectives of the invention, an improved hollow needle is provided with a recess at the rear end of the angular cutting surface. In addition, knives may be mounted to swivel to enable the knives to change their orientation with respect to the hollow needles slightly and thereby achieve the necessarily precise cutting alignment. A knife mount is also provided that may be either locked in a fixed position, or allowed to shift vertically in response to a vertical actuator such as a pneumatic cylinder so that both cut and cut/loop configurations of the tufting machine are possible without the need of a substantial inventory of varying parts.